cop87l84bc National Semiconductor Corporation, cop87l84bc Datasheet - Page 35

• Manufacturer Part Number: cop87l84bc
• Description: 8-bit Cmos Otp Microcontrollers With 16k Memory, Comparators, And Can Interface
• Manufacturer: National Semiconductor Corporation

Frame Formats
Comparators
The device has two differential comparators. Port L is used
for the comparators. The output of the comparators is multi-
plexed out to two pins. The following are the Port L assign-
ments:
L6
L5
L4
L3
L2
L1
L0
Additionally the comparator output can be connected inter-
nally to the L-Port pin of the respective positive input and
thereby generate an interrupt using the L-Port interrupt
structure (neg/pos. edge, enable/disable).
Note that in Figure 34 , pin L6 has a second alternate function
of supporting the PWM0 output. The comparator 2 output
MUST be disabled in order to use PWM0 output on L6.
Figure 34 shows the Comparator Block Diagram.
Comparator 2 output
Comparator 2 negative input
Comparator 2 positive input
Comparator 2 negative input
Comparator 1 output
Comparator 1 negative input
Comparator 1 positive input
(Continued)
FIGURE 32. Resynchronization 1
FIGURE 33. Resynchronization 2
35
COMPARATOR CONTROL REGISTER (CMPSL) (00D3)
These bits reside in the Comparator Register
The register contains the following bits:
CMP2SEL Selects which L port pin to use for comparator2
CMP2OE Enables comparator 2 output (“1”=enable),
CMP2RD Reads
CMP2EN Enables comparator 2 (“1”=enable). If compara-
CMP1OE Enables comparator 1 output (“1”=enable),
CMP1RD Reads
CMP2
Bit 7
SEL
CMP2
OE
negative input. (CMP2SEL = 0 selects L5;
CMP2SEL = 1 selects pin L3).
CMP2EN bit must be set to enable this function.
(CMP2EN=1) Read-only, reads as a “0” if com-
parator not enabled.
tor 2 is disabled the associated L-pins can be
used as standard I/O.
CMP1EN bit must be set to enable this function.
(CMP1EN=1) Read-only, reads as a “0” if com-
parator not enabled.
CMP2
RD
comparator
comparator
CMP2
EN
CMP1
OE
2
1
DS101137-67
CMP1
RD
output
output
CMP1
EN
www.national.com
DS101137-68
internally
internally
served
Re-
Bit 0